@Override
public void sendMessageOnce(String path, Object message, long time, ActorRef sender) {
synchronized (mailboxes) {
if (!scopes.containsKey(path)) {
if (sender != null) {
sender.send(new DeadLetter(message));
}
} else {
Mailbox mailbox = scopes.get(path).getMailbox();
mailbox.scheduleOnce(new Envelope(message, mailbox, sender), time);
}